CVE-2021-34866Public exploit

Privilege escalation via eBPF helper-map mismatch

Published Jan 25, 2022 · Updated Aug 4, 2024

Type confusion in the eBPF verifier in Linux Kernel 5.14-rc3 allows local users to execute arbitrary code in the kernel. check_map_func_compatibility() omits the helper-to-map type check, so ring-buffer helpers accept incompatible array or hash maps and perform invalid memory access. Exploitation requires low-privileged local code execution and can grant kernel-context control.

CVSS severity8.8
High
EPSS probability0.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in the eBPF verifier in Linux Kernel 5.14-rc3 allows local users to execute arbitrary code in the kernel. check_map_func_compatibility() omits the helper-to-map type check, so ring-buffer helpers accept incompatible array or hash maps and perform invalid memory access. Exploitation requires low-privileged local code execution and can grant kernel-context control.

The record

CVE
CVE-2021-34866
Published
Jan 25, 2022
Updated
Aug 4, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-843, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.14-rc3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.14-rc3

Published CVSS scores

8.8Zero Day InitiativeCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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